Method for controlling a digital device

ABSTRACT

A method for controlling a digital device according to the present application can control the device so as to execute a command corresponding to a single fingerprint or a plurality of fingerprints using a sheet capable of simultaneously recognizing a plurality of fingerprints. Accordingly, a user&#39;s usability can be greatly improved, and a complicated encryption function using a plurality of fingerprints can be implemented, so that the security of the digital device can be greatly improved.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a national phase entry under 35 U.S.C. § 371of International Application No. PCT/KR2017/013938 filed Nov. 30, 2017,published in Korean, which claims priority from both of KoreanApplication No. 10-2017-0145403 filed Nov. 2, 2017, and KoreanApplication No. 10-2016-0162148 filed Nov. 30, 2016, all of which areincorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a method for controlling a digitaldevice, and more particularly, to a method implemented in a digitaldevice equipped with a touch-screen display, which is a method forcontrolling a digital device capable of recognizing one or morefingerprints using a fingerprint recognition film which cansimultaneously recognize a plurality of fingerprints, and executing acommand corresponding to a single fingerprint or a plurality offingerprints, respectively.

BACKGROUND ART

Depending on generalization and use frequency increase of portablemobile devices such as smartphones and tablet PCs, security of thesedevices is becoming more important. Especially, it is more important tomaintain security in electronic commerce and banking fields using thesedevices. Biological information of a user, for example, fingerprint,iris, face, or voice, can be used to identify or authenticate a deviceuser for security maintenance. In recent years, portable mobile devicesto which a user authentication technology through the fingerprint isapplied have also been commercialized.

On the other hand, fingerprint recognition methods can be classifiedinto an optical method, an ultrasonic method, an electrostatic capacitymethod, an electric field measurement method and a heat sensing method,and the like. A digital device to which a conventional fingerprintrecognition method is applied requires a separate fingerprintrecognition sensor as an essential component, and when a conventionalfingerprint recognition sensor is combined with a button of a smartphone or the like, there has been a limitation capable of implantingonly a small number of functions in order to implement separatefunctions in addition to the security function through the fingerprintrecognition.

DISCLOSURE Technical Problem

It is an object of the present invention to provide a method forcontrolling a digital device equipped with a touch-screen display.

It is another object of the present invention to provide a method forcontrolling a digital device so as to execute a command corresponding toa single fingerprint or a plurality of fingerprints using a sheetcapable of simultaneously recognizing a plurality of fingerprints.

It is still another object of the present invention to provide a methodfor controlling a digital device so as to execute a commandcorresponding to a combination of a single fingerprint or a plurality offingerprints and a pressure when a fingerprint over a preset pressure isrecognized using a sheet capable of simultaneously recognizing aplurality of fingerprints and a pressure sensor.

The above objects of the present application and other objects can beall solved by the present application which is described in detailbelow.

Technical Solution

The conventional optical fingerprint recognition method can be dividedinto a so-called scattering method for detecting light scattered in aridge portion of a fingerprint in direct contact with a transparentfingerprint contact portion of the device, and a so-called totalreflection method for detecting light totally reflected from the surfaceof a fingerprint contact portion corresponding to a valley portion of afingerprint. In the former case, since light to be scattered must bedetected, it may be difficult to provide a light quantity sufficient toidentify the fingerprint pattern to the sensor, and the path of thescattered light may overlap the light path of the original light source,so that the contrast may be lowered. And, in the scattering method, atrapezoidal distortion caused by the light path difference also occurs.Devices having various structures have been proposed to solve the aboveproblems through various papers and patents, but it cannot be said thatthe scattering method is not suitable for portable mobile devicesbecause of the use of bulky prisms or the like. Also, in the lattercase, there is an advantage that a greater light quantity can be securedthan a method of detecting scattered light, but if the total reflectionpath is long in the process in which the totally reflected light towardthe sensor repeats the total reflection along the waveguide, the lightstotally reflected from adjacent fingerprints may interfere with eachother to lower the contrast. In addition, when the conventional totalreflection method is used, the size of the device can be increased dueto the necessity of separately installing a sensor or a prism, and thelike, and there is a problem that compatibility with the portable mobiledevice having a large area display is also poor, because input andoutput structures of the fingerprint recognition device are verylimited, as the sensor is positioned at the opposite end of one end ofthe waveguide where the light source is positioned.

Also, in general, a touch panel used in a digital device uses anelectrostatic or resistive touch sensor, where the electrostatic orresistive touch sensor has a technical limitation that it is difficultto recognize a fingerprint. Therefore, currently used digital devicesare equipped with a separate fingerprint recognition device togetherwith an electrostatic or resistive touch panel and generally performonly a limited function such as unlocking the device by using afingerprint recognition device installed in the device.

The present inventors have found that a single or a plurality offingerprints can be recognized using an optical fingerprint recognitionsheet. When the optical fingerprint recognition sheet is used, thefingerprint can be recognized on the display to reduce the size of adevice by requiring n₀ separate fingerprint recognition device. Inaddition, since a plurality of fingerprints can be recognized on a largearea display, security of a digital device can be greatly improved, andthe digital device makes it to execute a command corresponding to asingle fingerprint or a plurality of fingerprints only by touching thefingerprint on the display, whereby it is possible to provide a methodfor controlling a digital device in which the user's convenience isgreatly improved.

In order to solve the problems of the prior art described above and toachieve the above objects, the present application provides a method forcontrolling a digital device using a sheet capable of simultaneouslyrecognizing a plurality of fingerprints, which comprises, in a singlelayer, a first light control part capable of providing light alwaystotally reflected from a surface layer of the sheet; and a second lightcontrol part capable of providing light whose total reflection isdetermined according to a fingerprint pattern in contact with thesurface layer of the sheet to the surface layer of the sheet by changinga part of the light provided from the first light control part andtotally reflected from the surface layer of the sheet at a predeterminedangle and emitting it.

Advantageous Effects

The method for controlling a digital device according to the presentapplication can control the device to execute a command corresponding toa single fingerprint or a plurality of fingerprints using a sheetcapable of simultaneously recognizing a plurality of fingerprints. Thesheet of the present application is a sheet which can providefingerprint information with high contrast and recognize a plurality offingerprint patterns without any influence on each other, where it canbe applied to a digital device having a large area screen displaydevice, thereby greatly improving the user's usability, and it canimplement a complicated encryption function using a plurality offingerprints, thereby greatly improving the security of the digitaldevice.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 schematically shows a cross-section of a sheet for opticalfingerprint recognition according to one embodiment of the presentapplication and a device comprising the same.

FIG. 2 is an image of a fingerprint photographed using a sheet accordingto one embodiment of the present application.

FIG. 3 is a schematic diagram showing fingerprint recognition accordingto one embodiment of the present application.

Hereinafter, a sheet according to one embodiment of the presentapplication and a device comprising the same will be described in detailwith reference to the accompanying drawings. For ease of explanation,the size or shape of each configuration shown may be exaggerated orreduced.

BEST MODE

The present application relates to a method for controlling a digitaldevice. In the present application, the term digital device includes,for example, all devices that perform at least one or more oftransmission, reception, processing and output of data, contents,services, applications, and the like. The digital device can besubjected to pairing or connecting (hereinafter, referred to as‘pairing’) with another digital device, an external server, or the likethrough a wire/wireless network, thereby transmitting/receivingpredetermined data. At this time, if necessary, the data may beappropriately converted before the transmission/reception. The digitaldevice may include, for example, both of a standing device such as anetwork TV, an HBBTV (hybrid broadcast broadband TV), a smart TV, anIPTV (internet protocol TV) and a PC (personal computer), and a mobiledevice (or handheld device) such as a PDA (personal digital assistant),a smartphone, a tablet PC and a notebook.

An exemplary digital device control method of the present applicationmay be a method implemented in a digital device having a touch-screendisplay. The touch-screen display may comprise a sheet 600 capable ofsimultaneously recognizing a plurality of fingerprints, the sheet 600may be a sheet comprising: a lower base layer; and a light control layer200 positioned on the lower base layer 300 and having a first lightcontrol part 210 and a second light control part 220, the first lightcontrol part 210 may be provided so as to emit the light that isincident on the lower surface of the first light control part 210 at afirst incident angle (θ₀) as the light with a second incident angle(θ_(A)) different from the first incident angle (θ₀) and the secondlight control part 220 may be provided so as to emit the light that isincident on the upper surface of the second light control part 220 atthe second incident angle (θ_(A)) as the light with the second incidentangle (θ_(A)) and the light with a third incident angle (θ_(B))different from the second incident angle (θ_(A)). As described below,the sheet 600 may be a sheet which can comprise a base layer having adifferent refractive index from each other, emit light incident at afirst incident angle as light with a second incident angle differentfrom the first incident angle and recognize a fingerprint on thedisplay. In one example, the sheet 600 of the present application may bean optical fingerprint recognition film.

FIG. 3 is a schematic diagram showing a digital device to which thecontrol method of the present application is applied. The control methodof the present application is a control method of a digital device (1)having a touch-screen display, where the touch-screen display maycomprise a sheet (2) capable of simultaneously recognizing a pluralityof fingerprints (10, 20, 30). The control method may comprise a step ofrecognizing one or more fingerprints and executing a commandindependently corresponding to a single fingerprint or a plurality offingerprints. The method for controlling a digital device of the presentapplication can simultaneously recognize a plurality of fingerprintsusing the sheet 2 and thus control the digital device 1 so as to executevarious commands stored therein only by touching the fingerprint on thedisplay, thereby greatly improving the user's usability. In addition,since the fingerprint can be directly recognized on the display, it ispossible to reduce the volume of the digital device without any separatefingerprint recognition device, thereby making it possible tominiaturize the product as compared with the case of using theconventional fingerprint recognition device.

In one example, the control method of the present application canexecute a corresponding command by applying one or more heuristicmethods to one or more recognized fingerprints. In the presentapplication, the term heuristic method (approximation, discovery orintuition method) may mean a hypothetical decision based on aprobability and may mean a statistical algorithm for determining acommand corresponding to a user's specific behavior. For example, whenthe user sweeps on a touch-screen the screen to the left, the heuristicmethod may mean a method such as a method of moving the screen bydetermining the user's intention even if the user does not move ithorizontally exactly.

Also, in the control method of the present application, one or moreheuristic methods may be a heuristic method for determining acorresponding command for a single fingerprint or a combination of aplurality of fingerprints, respectively. In the case of executing thecorresponding command independently by applying one or more heuristicmethods to a single fingerprint or a plurality of fingerprints, evenwhen the entire fingerprint is not recognized and only a part of thefingerprint is recognized or when positional information on a pluralityof fingerprints is different, it is possible to execute a commandcorresponding to the user's intention, thereby improving the user'susability.

In one example, a command independently corresponding to a singlefingerprint or a plurality of fingerprints may comprise unlocking thedigital device. In the present application, the fact that a command isindependently corresponding to a fingerprint may mean a state in whichthe same command and/or different commands are inputted to be executedfor an individual fingerprint or a combination of differentfingerprints. In the present application, the locking of the digitaldevice may mean a locked mode state implemented for the purpose ofavoiding activation due to the user's carelessness, or security. In thelocked mode state, the digital device may be in an unusable state otherthan a limited function such as an emergency call. The control method ofthe present application can simultaneously unlock a digital device bysimultaneously recognizing a plurality of fingerprints and implement acomplicated encryption function using the plurality of fingerprints.This can enhance the security of digital devices.

In one example of the present application, the command independentlycorresponding to a single fingerprint or a plurality of fingerprints maybe execution of an application. The application may mean a program runon a digital device, which may be exemplified by a utility program, aviewer program and/or a game, and the like, running on the digitaldevice, but is not limited thereto. An exemplary application may includetelephone, video conferencing, email, instant messaging, blogging,digital photography, digital video recording, web browsing, digitalmusic playback, digital video playback or digital keyboard playing, butis not limited thereto. By independently executing an application for asingle fingerprint or a plurality of fingerprints of a user, the usercan run the desired application with a single touch to greatly improveusability.

In another example of the present application, the command independentlycorresponding to a single fingerprint or a plurality of fingerprints maybe a one-dimensional vertical screen scrolling command, atwo-dimensional screen translation command, a screen enlargement orreduction command, a command to convert from displaying a first item inan item set to displaying a next item in the item set or a command toconvert from displaying a first item in an item set to displaying aprevious item in the item set, but is not limited thereto.

In one example, the control method of the present application mayfurther comprise a step of inputting a command corresponding to a singlefingerprint or a plurality of fingerprints by a user. The command may bea command previously input into the digital device by the user, whichmay be a command selected by the user or a command optionally designatedby the user among commands previously input in the digital device of thepresent application. As the user selects a command to be executed on theindividual fingerprint or the plurality of fingerprints as above, it ispossible to be controlled so as to execute a command that the user wantson the individual fingerprint or the plurality of fingerprints, therebyimproving the usability for the digital device.

In another example of the present application, the touch-screen displaymay comprise a pressure sensor on the back of the display. When afingerprint is contacted on the display, the pressure sensor may mean asensor capable of measuring a pressure applied to the display from thefingerprint. The pressure sensor is not particularly limited as long asit can sense the degree of pressure applied to the display. An exemplarypressure sensor may include a capacitive pressure sensor, apiezoelectric pressure sensor, a microelectromechanical system(MEMS)-based pressure sensor, a pressure transducer, a silicon-basedpressure sensor, a strain gage, an optical pressure sensor, an inductivepressure sensor, or pressure sensors implemented using other suitablepressure sensing techniques, but is not limited thereto.

When the digital device of the present application comprises a pressuresensor, the digital device may have a preset pressure value. Thepressure value may mean an intensity of contact of the fingerprintapplied on the touch-screen display, and may mean a force per unit areaof the contact. The preset pressure value may be any value set by theuser, which may have different values depending on individual users.

In one example, when a fingerprint over a preset pressure of the digitaldevice is recognized, the control method of the present application canexecute a command independently corresponding to a combination of asingle fingerprint or a plurality of fingerprints and pressure. Inaddition to the command corresponding to the single fingerprint or theplurality of fingerprints described above, the method executes a commandindependently corresponding to a combination of the single fingerprintor the plurality of fingerprints and the pressure, whereby more variouscommands can be input and various commands which can be implemented inthe digital device can be driven only by touching the touch-screendisplay.

In another example of the present application, the digital device of thepresent application may comprise a motion sensor therein. The motionsensor may be a sensor for sensing a user's movement. The motion sensoris not particularly limited as long as it can sense the user's movement.An exemplary motion sensor can be exemplified by a 3-axis accelerometer,a 3-axis gyroscope, a geomagnetic sensor, and the like, but is notlimited thereto.

When the digital device of the present application comprises a motionsensor, the control method of the present application can execute acommand independently corresponding to a single fingerprint or aplurality of fingerprints and a user's movement. In addition to thecommand corresponding to the single fingerprint or the plurality offingerprints described above, the method executes a commandindependently corresponding to a combination of the single fingerprintor the plurality of fingerprints and the user's movement, whereby morevarious commands can be input and various commands which can beimplemented in the digital device can be driven only by touching thetouch-screen display.

Subsequently, a fingerprint recognition sheet applied to the controlmethod of the digital device of the present application will bedescribed.

In one example related to the present application, the sheet of thepresent application may be a sheet for optical fingerprint recognitionor a sheet for fingerprint input. As described below, the sheet of thepresent application can be configured so that light derived from anexternal light source can be present (incident) on the sheet surfacelayer with two lights (rays) with different angles. One of the lights(rays) can be always totally reflected in the sheet, and the other canbe identified by the sensor positioned on the lower part of the sheet,by being determined for total reflection at the surface layer of thesheet depending on a pattern of a material contacting the outside of thesheet and penetrating the lower part of the sheet after being totallyreflected.

In this regard, FIG. 1 schematically shows a cross-section of a sheet600 for optical fingerprint recognition according to one embodiment ofthe present application and a device comprising the same. The presentapplication will be described with reference to FIG. 1 as follows.

The sheet 600 of the present application may comprise a lower base layer300 and a light control layer 200 positioned on the lower base layer300. In the present application, the term “on” or “above” used inconnection with the interlayer lamination position may mean includingnot only the case where a configuration is formed directly on anotherconfiguration but also the case where a third configuration isinterposed between these configurations.

The light control layer 200 comprises a first light control part 210 anda second light control part 220. The light control parts 210, 220 may beconfigurations provided so as to perform a predetermined function onlyon light incident at a specific angle. Accordingly, as described below,the first light control part 210 can provide light that always totallyreflects to the surface layer of the sheet 600. Furthermore, the secondlight control part 220 can provide to the surface layer of the sheet 600light in which the total reflection is determined depending on afingerprint pattern in contact with the sheet surface layer.

As shown in FIG. 1, the first light control part 210 can emit the lightincident at a first incident angle (θ₀) with respect to the lowersurface of the first light control part 210 as the light (A) with asecond incident angle (θ_(A)) different from the first incident angle(θ₀). In one example, the exit surface of the first light control part210, from which the light with the second incident angle (θ_(A)) isemitted, may be any other surface other than the lower surface of thefirst light control part 210. More specifically, the sheet 600 of thepresent application can be configured so that the light with the secondincident angle (θ_(A)) can be emitted from the side surface and/or uppersurface of the first light control part 210. In addition, the secondlight control part 220 can emit the light incident at a second incidentangle (θ_(A)) with respect to the upper surface of the second lightcontrol part 220 as both the light (A) with a second incident angle(θ_(A)) and the light (B) with a third incident angle (θ_(B)) differentfrom the second incident angle (θ_(A)). In one example, the exit surfaceof the second light control part 220, from which the light with thesecond incident angle (θ_(A)) and the light with the third incidentangle (θ_(B)) are emitted, may be any other surface other than the lowersurface of the second light control part 220. More specifically, thesheet 600 of the present application can be configured so that the light(A) with the second incident angle (θ_(A)) and the light (B) with thethird incident angle (θ_(B)) can be emitted from the side surface and/orupper surface of the second light control part 220. In the presentapplication, the unit of angle is ° (degree), and the term “incidentangle” is an angle formed by the traveling direction of light from thenormal to the sheet 600 (or light-entering layer or light-enteringsurface) placed on the horizontal plane, which may mean more than 0° toless than 90°. The term incident angle may also be referred to as anexit angle depending on the relative position of each configurationalong the traveling direction of light. In the present application, the“lower surface” may mean one surface of a transparent base layer, alight control layer 200 or a light control part which faces or contactsthe lower base layer 300, and the “upper surface” may mean the oppositeone surface of a transparent base layer, a light control layer 200 or alight control part, having the relevant lower surface. The lower surfaceor the upper surface may be referred to as a light-entering surface oran incident surface, and a light-emitting surface or an exit surface,depending on the traveling path of light.

Since the light control layer 200 of the present application can bedivided into two parts 210, 220 in which the angle or path of light, andthe like can be controlled differently from each other as above, twolights (A and B) having different angles toward the transparent baselayer 100 positioned on the light control layer 200, specifically, withrespect to the transparent base layer 100, and more specifically, thesurface layer of the sheet 600 can be provided (emitted), as in FIG. 1.In the present application, the surface layer of the sheet 600 may mean,for example, the upper surface of the transparent base layer 100 incontact with air, or the upper surface of the transparent base layer 100in direct or indirect contact with an object having a pattern such as afingerprint 700.

In one example, the sheet 600 of the present application may furthercomprise a transparent base layer 100 that a fingerprint can contact.When the sheet 600 comprises a transparent base layer 100, thetransparent base layer 100 may be located on the light control layer200. That is, the sheet 600 may sequentially comprise a lower base layer300, a light control layer 200 and a transparent base layer 100. In thepresent application, the term “transparent” used in relation to theproperties of the layer may mean a case where the lower limit of thetransmittance to visible light having a wavelength of 380 nm to 780 nmis 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90%or more, or 95% or more, and the upper limit is about 100%, which is ina range of less than 100%.

In the case of comprising the transparent base layer 100, the firstlight control part 210 can emit the light incident on the lower surfaceof the first light control part 210 at the first incident angle (θ₀)through the lower base layer 300 as the light with the second incidentangle (θ_(A)) different from the first incident angle (θ₀) toward thetransparent base layer 100. In one example, the light with the secondincident angle (θ_(A)) can be emitted from the upper surface and/or theside surface of the first light control part 210. Furthermore, when thetransparent base layer 100 is directly positioned on the light controllayer 200, the lower surface of the transparent base layer 100 can bethe light incident surface with respect to the light with the secondincident angle (θ_(A)).

In the case of comprising the transparent base layer 100, the secondlight control part 220 can emit the light incident on the upper surfaceof the second light control part 220 at the second incident angle(θ_(A)) through the transparent base layer 100 as the light (A) with thesecond incident angle (θ_(A)) and the light (B) with the third incidentangle (θ_(B)) different from the second incident angle (θ_(A)) towardthe transparent base layer 100. In one example, the light with thesecond incident angle (θ_(A)) and the light with the third incidentangle (θ_(B)) can be emitted from the upper surface and/or the sidesurface of the second light control part 220. That is, the second lightcontrol part 220 can convert a part of the light (A) having an incidentangle of θ_(A) into the light (B) having an incident angle of θ_(B). Theconversion degree, that is, the ratio, in which the light (A) incidentat the angle θ_(A) is converted to the light (B) with the angle θ_(B),is not particularly limited, which may be suitably adjusted in a rangeof more than 0% to less than 100%. At this time, θ_(A) and θ_(B) may bean (incident) angle that the light emitted from the first light controlpart 210 and the light emitted from the second light control part 220have each in the inside of the transparent base layer 100.

The information of the fingerprint 700 in contact with the transparentbase layer 100 can be read by the above configuration. Specifically, apath of light for allowing the fingerprint information to be readaccording to one example of the present application will be described asfollows. That is, the light incident on the first light control part 210from the light source 500 via the lower base layer 300 is emitted as thelight with the angle θ_(A) that can be always totally reflected from theupper surface of the transparent base layer 100 into the inside of thesheet 600 by the first light control part 210, and the light with theangle θ_(A) emitted from the first light control part 210 is totallyreflected from the upper surface of the transparent base layer 100irrespective of whether or not the fingerprint 700 and the transparentbase layer 100 contact, and is incident on the second light control part220. And, the second light control part 220 converts a part of the lightincident at the angle θ_(A) into the light with the angle θ_(B) andemits the light to the transparent base layer 100, and the remainingunconverted light is totally reflected from the upper surface of thelower base layer 300, for example, the interface between the lightcontrol layer 200 and the lower base layer 300. Thereafter, the lightwith the angle θ_(B) emitted to the transparent base layer 100 istransmitted (or transmitted and scattered) from the ridge 710 of thefingerprint 700, which is a contact portion of the transparent baselayer 100 and the fingerprint 700, and is totally reflected from thevalley 720 of the fingerprint 700, which is a non-contact portion of thetransparent base layer 100 and the fingerprint 700. The light with theangle θ_(B) totally reflected from the valley portion of the transparentbase layer 100 and the fingerprint 700 can pass through the lightcontrol layer 200 and the lower base layer 300, and reach the sensor tobe identified. In the present application, the term “interface” may meana boundary surface between two adjacent layers, or a boundary surfacebetween heterogeneous media placed on a path through which light passes.

According to one embodiment of the present application, in order toperform functions as above, the sheet 600 of the present application maybe constituted or provided as follows.

In one example, the first light control part 210 and the second lightcontrol part 220 may comprise each a diffractive optical element or arefractive optical element.

The refractive optical element may mean an element having acharacteristic in which the traveling direction or angle of light isdetermined by the refractive index difference with the adjacent medium.When the light control part of the present application is a refractiveoptical element, the light control part may be configured inconsideration of refractive indexes between the respective layers so asto satisfy the optical path described in the present application.

The diffractive optical element may mean an element having acharacteristic in which the traveling direction or angle of light isdetermined by the shape of the pattern and the spacing between thepatterns. When the light control part of the present application is adiffractive optical element, the light control part may be configured inconsideration of refractive indexes between the respective layers anddiffraction patterns so as to satisfy the optical path described in thepresent application.

In one example, the light control layer 200 of the present applicationmay comprise a diffractive optical element. Specifically, the firstlight control part 210 and the second light control part 220 maycomprise diffractive optical elements having different functions fromeach other, where the diffractive optical element may be a holographicoptical element (HOE) in the form of a film. The holography is atechnique for recording an interference pattern in a photosensitivemedium to reproduce a three-dimensional image called a hologram. Also,the holographic film may mean a film on which a holographic recording isrecorded, and may mean a film capable of recording an interferencepattern on a film having very small photosensitive particles usingrecording light and reproducing it using reproduction light. Since theholographic film may perform the function only for the recorded lightand may not perform the required function for light other than therecorded light, when the holographic film is used for the first lightcontrol part 210 and the second light control part 220, it isparticularly advantageous to adjust the angle, the optical path and/orthe light quantity of light required in the present application.

The holographic film may comprise a photosensitive material as arecording medium. As the photosensitive material, a photopolymer, aphotoresist, a silver halide emulsion, a dichromated gelatin, aphotographic emulsion, a photothermoplastic or a photorefractivematerial, and the like can be used. In one example, the holographic filmmay comprise a photopolymer as a photosensitive material, and may be,specifically, a film consisting only of a photopolymer, or a film with adouble-layered structure comprising a photopolymer layer and a substratefor the layer together. In this case, the substrate used together withthe photopolymer may be a transparent substrate and may be, for example,a substrate comprising polycarbonate (PC), polypropylene (PP), polyamide(PA), polyethylene terephthalate (PET) or triacetyl cellulose (TAC), andthe like, but is not particularly limited.

In one example, the diffraction efficiencies of the first light controlpart 210 and the second light control part 220 may be the same ordifferent from each other. Specifically, the first light control part210 may have the same diffraction efficiency in its entire area and thesecond light control part 220 may also have the same diffractionefficiency in its entire area, where the diffraction efficiencies of thelight control parts 210, 220 may be the same or different from eachother.

In one example, the first light control part 210 and the second lightcontrol part 220 may be some regions formed by changing only angles ordiffraction patterns of recording light on one layer, respectively.Alternatively, the light control layer 200 may also be formed bydirectly attaching the first light control part 210 and the second lightcontrol part 220 or by attaching them via another medium, so that thefirst light control part 210 and the second light control part 220,which are separately manufacture, may form a single layer.

When the transmittance described above is satisfied, the kind of thetransparent base layer is not particularly limited. For example, it maycomprise glass or a polymer resin. As the polymer resin, a polyesterfilm such as PC (polycarbonate), PEN (poly(ethylene naphthalate)) or PET(poly(ethylene terephthalate)), an acrylic film such as PMMA(poly(methyl methacrylate)) or a polyolefin film such as PE(polyethylene) or PP (polypropylene) may be used, without being limitedthereto. In one example, the transparent base layer may have aconfiguration in which a number of glass or polymer resins arelaminated. Even in the case of having such a laminated structure, thetransparent base layer may be provided so as to perform the functionsrequired in the present application and satisfy the following relationalexpressions.

In one example, the lower base layer 300 may be a pressure-sensitiveadhesive layer satisfying refractive indexes and relational expressionsto be described below. The kind or composition of the pressure-sensitiveadhesive layer is not particularly limited and may be, for example, anacrylic pressure-sensitive adhesive layer or a siliconepressure-sensitive adhesive layer. In another example, the lower baselayer 300 may further comprise, in addition to the pressure-sensitiveadhesive material, the above-described transparent resin film, wherethese may function as a substrate for the pressure-sensitive adhesivematerial, or may be used for the purpose of imparting other functions.Even in the case of having such a configuration, the lower base layer300 may be provided so as to perform the function required in thepresent application and satisfy the following relational expressions.

In the present application, the lower base layer 300, the light controllayer 200 and the transparent base layer 100 may have the same ordifferent refractive indexes. In one example, the layers 100, 200, 300may each independently have a refractive index in a range of more than 1to 5 or less, or more than 1 to 3 or less, and the interlayer refractiveindex difference may be 0.0001 to 2 or less. In the case of the lightcontrol layer 200, the refractive indexes of the first light controlpart 210 and the second light control part 220 can be adjusted to be thesame or different in a range that can perform the functions required inthe present application.

In one example, the refractive index of the lower base layer 300 may beless than the refractive index of the light control layer 200 and/or therefractive index of the transparent base layer 100. That is, the lowerbase layer 300 may be a low refractive layer. Although not particularlylimited, when the refractive index relationship is satisfied, therefractive index difference between the lower base layer 300 and thelight control layer 200 may be 0.1 or less.

In one example, the transparent base layer 100 may have a higherrefractive index than the light control layer 200. Although notparticularly limited, when the refractive index relationship issatisfied, the refractive index difference between the transparent baselayer 100 and the light control layer 200 may be 0.05 or less.

In the present application, the thicknesses of the lower base layer 300,the light control layer 200, the transparent base layer 100, or otherconstituents that may be contained therein is not particularly limited.For example, if the function of the sheet 600 described in the presentapplication is exerted, the thickness of the structure is not limited,where for example, the lower limit may be 0.1 μm or more, or 1 μm ormore and the upper limit may be 1,000 μm or less or 500 μm or less.

The sheet 600 of the present application may be configured such that thelight with the angle θ_(A) always totally reflected in the sheet 600 maybe present. That is, the light with θ_(A) can be always totallyreflected from the upper surface of the transparent base layer 100, andthe light with θ_(A) can also be totally reflected from the uppersurface of the transparent base layer 100, can pass through the lightcontrol layer 200 from the transparent base layer 100 and can be totallyreflected from the upper surface of the lower base layer 300, forexample, the interface between the light control layer 200 and the lowerbase layer 300.

Specifically, the sheet 600 of the present application can be configuredso that the light with the angle θ_(A) emitted from the first lightcontrol part 210 toward the transparent base layer 100 satisfies thefollowing relational expressions 1 and 2. The relational expressionsdescribed below can be obtained using Snell's law.θ_(A)>(180°/π)×sin⁻¹(n ₀ /n ₁)  [Relational Expression 1]

Relational Expression 1 above defines the condition that the light withthe angle θ_(A) traveling from the transparent base layer 100 to the airside is totally reflected from the upper surface of the transparent baselayer 100, for example, the interface between the transparent base layer100 and the air layer. In Relational Expression 1 above, n₀ is 1 as therefractive index of air, and n₁ is the refractive index of thetransparent base layer 100.θ_(A)>(180°/π)×sin⁻¹(n ₃ /n ₁)  [Relational Expression 2]

Relational Expression 2 above defines the condition that the light withthe angle θ_(A) totally reflected from the upper surface of thetransparent base layer 100 passes through the light control layer 200from the transparent base layer 100 and is totally reflected from theupper surface of the lower base layer 300 such as the interface betweenthe light control layer 200 and the lower base layer 300. In RelationalExpression 2 above, n₁ is the refractive index of the transparent baselayer 100, and n₃ is the refractive index of the lower base layer 300.

In one example, in order to satisfy Relational Expression 2 above, thelight with the angle θ_(A) totally reflected from the upper surface ofthe transparent base layer 100 must penetrate the upper surface of thetransparent base layer 100 and/or the light control layer 200. Forexample, when the refractive index of the transparent base layer 100 islarger than the refractive index of the light control layer 200, thetotal reflection should not occur at the interface between thetransparent base layer 100 and the light control layer 200, and thusθ_(A) must satisfy the following relational expression 3.θ_(A)<(180°/π)×sin⁻¹(n ₂ /n ₁)  [Relational Expression 3]

Relational Expression 3 above defines the condition that the totalreflection does not occur at the interface between the transparent baselayer 100 and the light control layer 200. In Relational Expression 3above, n₁ is the refractive index of the transparent base layer 100, n₂is the refractive index of the first light control part 210 or thesecond light control part 220 in the light control layer 200, and n₁ islarger than n₂.

In the present application, the light with the angle θ_(A) may be lighttotally reflected from the upper surface (contact surface) of thetransparent base layer 100 where the transparent base layer 100 and anobject contact directly, even when the object having a pattern with adifferent height contacts the transparent base layer 100. In order tosatisfy this, the angle θ_(A) of the light emitted from the first lightcontrol part 210 may satisfy the following relational expression 4.θ_(A)>(180°/π)×sin⁻¹(n _(h) /n ₁)  [Relational Expression 4]

In Relational Expression 4 above, n₁ is the refractive index of thetransparent base layer 100, and n_(h) is the refractive index of theportion whose the object having a pattern with a different height is indirect contact with the transparent base layer 100. At this time, theobject having a pattern with a different height may be a fingerprint 700and the portion whose the object having a pattern with a differentheight is in direct contact with the transparent base layer 100 may be aridge 710 of the fingerprint 700. On the other hand, the non-contactportion of the object having a pattern with a different height with thetransparent base layer 100 may be a valley 720 of the fingerprint 700,and since the valley portion is occupied by the air, the refractiveindex of the valley portion can be regarded as 1 (=n₀).

As described above, in the present application, the sheet 600 isprovided so as to be capable of providing the totally reflected lightalways totally reflected in the sheet 600 so that the light with theangle (θ_(A)) provided from the first light control part 210 satisfiesthe predetermined relational expressions. On the other hand, in thepresent application, the light with the angle (θ_(A)) is light in whichthe total reflection is performed irrespective of whether or not thefingerprint 700 contacts, so that the light quantity in the sheet 600can be maintained at a certain level. And, as described below, since thelight with the angle (θ_(B)) used for fingerprint recognition originatesfrom the light with the angle (θ_(A)), the light with the angle (θ_(B))for generating the fingerprint image can also have a light quantity keptconstant in the sheet 600 irrespective of whether or not the fingerprint700 contacts.

In the present application, the second light control part 220 may be aconfiguration to provide light (B) generated regardless of whether ornot the fingerprint 700 contacts.

Specifically, the second light control part 220 may be a configurationto provide light with an angle (θ_(B)) at which the total reflection onthe upper surface of the transparent base layer 100 is determineddepending on the presence or absence of an object existing on thetransparent base layer 100. That is, the light with the angle (θ_(B))may be light that when the object does not exist on the transparent baselayer 100, it is totally reflected from the upper surface of thetransparent base layer 100, for example, the interface between thetransparent base layer 100 and the air, but when the object having apattern with a different height contacts the transparent base layer 100,it is transmitted (or transmitted and scattered) from a direct contactportion (ridge) of the object with respect to the transparent base layer100.

In one example, the sheet 600 of the present application may be providedso that the light with the angle (θ_(B)) may be totally reflected fromthe upper surface of the transparent base layer 100, for example, theinterface between the transparent base layer 100 and the air, bysatisfying the following relational expression 5. And, when the objecthaving a pattern with a different height contacts the transparent baselayer 100, it may be configured so that the light with the angle (θ_(B))may be transmitted (or transmitted and scattered) from the upper faceportion of the transparent base layer 100 in direct contact with theobject, by satisfying the following relational expression 6.θ_(B)>(180°/π)×sin⁻¹(n ₀ /n ₁)  [Relational Expression 5]θ_(B)<(180°/π)×sin⁻¹(n _(h) /n ₁)  [Relational Expression 6]

However, in Relational Expressions 5 and 6 above, n₀ is 1 as therefractive index of air, n₁ is the refractive index of the transparentbase layer 100, and n_(h) is a refractive index of a ridge portion indirect contact with the transparent base layer 100 in the object havinga pattern with a different height. As described above, since the valleyportion in the object having a pattern with a different height, which isa non-contact portion with the transparent base layer 100, is occupiedby the air, the refractive index of the non-contact portion can beregarded as 1 (=n₀).

Furthermore, in the present application, the sheet 600 may be providedsuch that the light with the angle (θ_(B)) emitted from the second lightcontrol part 220 and incident on the transparent base layer 100 may betotally reflected from the upper surface of the transparent base layer100 and then penetrate the upper surface of the light control layer 200.When the refractive index of the transparent base layer 100 is largerthan the refractive index of the light control layer 200, the totalreflection must not occur at the interface between the transparent baselayer 100 and the light control layer 200, so that the angle θ_(B) cansatisfy the following relational expression 7.θ_(B)<(180°/π)×sin⁻¹(n ₂ /n ₁)  [Relational Expression 7]

Relational Expression 7 above defines a condition in which the totalreflection does not occur at the interface between the transparent baselayer 100 and the light control layer 200. In Relational Expression 7above, n₁ is the refractive index of the transparent base layer 100, n₂is the refractive index of the first light control part 210 or thesecond light control part 220 in the light control layer 200, and n₁ islarger than n₂.

In addition, the sheet 600 of the present application may be provided sothat when the light with the angle θ_(B) emitted from the second lightcontrol part 220 is totally reflected from the upper surface of thetransparent base layer 100, it can penetrate the lower base layer 300.The light penetrating the lower base layer 300 can be recognized by thesensor. In order that the light capable of penetrating the lower baselayer 300 is present in the sheet 600, when the light with θ_(B) istotally reflected from the surface layer of the transparent base layer100 and enters the upper surface of the lower base layer 300 via thetransparent base layer 100 and the light control layer 200, the totalreflection should not occur at the interface between the light controllayer 200 and the lower base layer 300. In this connection, θ_(B) cansatisfy the following relational expression 8.θ_(B)<(180°/π)×sin⁻¹(n ₃ /n ₁)  [Relational Expression 8]

Relational Expression 8 above defines a condition that the lightpenetrating the lower base layer 300 is present. In RelationalExpression 8 above, n₁ is the refractive index of the transparent baselayer 100, and n₃ is the refractive index of the lower base layer 300.

When the angle θ_(B) of the light totally reflected from the uppersurface of the transparent base layer 100 as above satisfies RelationalExpressions 7 and 8 above, the sensor existing in the lower part of thesheet 600 can recognize the light penetrating the lower base layer 300,as shown in FIG. 1. That is, the sheet 600 of the present applicationallows the user's fingerprint 700 to be recognized using a method ofidentifying a difference in light quantity between the light totallyreflected from the upper surface of the transparent base layer 100 incontact with air and the light transmitted (or transmitted andscattered) from the contact portion of the transparent base layer 100and the object among the light with an angle (θ_(B)) emitted from thesecond light control part 220.

As such, the present application does not directly use the light alwaystotally reflected in the sheet 600 for fingerprint identification.Specifically, when a part of the light with the angle θ_(A) providedfrom the first light control part 210 is converted into the light withthe angle θ_(B) different from θ_(A) by the second light control part220 and emitted toward the transparent base layer 100, so that thealways totally reflected light may exist, and the light emitted towardthe transparent base layer 100 at the incident angle θ_(B) is totallyreflected from the upper surface of the transparent base layer 100 incontact with an external object to the inside of the sheet 600 andtransmitted (or transmitted and scattered) to the outside of the sheet600, the present application uses the light quantity difference of theselights for fingerprint identification. That is, the difference betweenthe light quantity of the light totally reflected from the non-contactportion with the fingerprint and traveling to the sensor and the lightquantity of the light transmitted (or transmitted and scattered) fromthe contact portion with the fingerprint and reduced, among the lightsat the angle θ_(B), is used for fingerprint identification.

Furthermore, in the present application, the light with the angle θ_(B)is generated from the light always totally reflected in the sheet 600regardless of the presence or absence of the fingerprint. Therefore, inthe present application, the light quantity of the light used foridentifying the fingerprint can be kept constant by using the lightalways totally reflecting the inside of the sheet 600, and consequently,the difference between the light totally reflected from the interface ofthe transparent base layer 100 and the air, and the light transmitted(or transmitted and scattered) from the direct contact portion of thetransparent base layer 100 and the object, among the lights with theangle (θ_(B)), can be more clearly recognized by the sensor. Besides, inthe present application, the light totally reflected from the interfacebetween the transparent base layer 100 and the air and the lighttransmitted (or transmitted and scattered) from the contact portion ofthe transparent base layer 100 and the object, among the lights with theangle (θ_(B)) generated regardless of the presence or absence of thefingerprint, are used for fingerprint identification, so that even if anumber of fingerprint patterns are in contact with the transparent baselayer 100, they can be identified without being influenced by eachother.

In one example, a projected area (S1) of the first light control part210 may be smaller than a projected area (S2) of the second lightcontrol part 220. In the present application, the term “projected area”may mean, on observing the sheet 600 from the upper part or the lowerpart in a direction parallel to the normal direction of its surface, anarea in which the relevant configuration is viewed, and for example, anorthogonal projection area. Therefore, the increase or decrease of theactual area due to the unevenness of the area comparison targetconfiguration or the like is not considered. Although not particularlylimited, S1:S2 may be in a range of 5 to 40:60 to 95.

In another example related to the present application, the digitaldevice of the present application may further comprise a light sourcepart 500. The light source part 500 means a configuration capable ofradiating light toward the sheet 600. The specific configuration of thelight source part 500 is not particularly limited as long as the abovefunction can be performed. As in FIG. 1, the light source part 500 maybe located on one surface of the sheet 600 lower base layer 300, morespecifically, on the opposite one surface of one surface of the lowerbase layer 300 where the first light control part 210 contacts. Thelight incident from the light source part 500 is incident on the firstlight control part 210 of the light control layer 200 via the lower baselayer 300, whereby the light that can be always totally reflected in thesheet 600 can be provided to the sheet 600. In one example, the lightincident on the first light control part 210 may be vertical to thebottom surface of the first light control part 210. In the presentapplication, the term “vertical” means a substantial verticalness in arange that does not impair the desired effect, which is used, forexample, in consideration of manufacturing error or variation, and thelike. At this time, the error or variation may be within ±10°, within±8°, within ±6°, within ±4°, within ±2°, within ±1°, within ±0.5°,within ±0.2°, or within ±0.1°.

In one example, the device may further comprise a sensor part 400. Thesensor part 400 may mean a configuration for sensing the lightpenetrating the lower base layer 300. The configuration of the sensorpart is not particularly limited as long as the above function can beperformed, where a known sensor can be used. As in FIG. 1, the sensorpart 400 may be located on one surface of the sheet 600 lower base layer300, more specifically, on the opposite one surface of one surface ofthe lower base layer 300 in which the second light control part 220contacts. As described above, the light totally reflected in thetransparent base layer 100 portion that directly contacts thefingerprint 700, except for the totally reflected light in the sheet600, can penetrate the lower base layer 300 to reach the sensor part400, where the sensor part 400 can recognize the pattern of the objectcontacting the transparent base layer 100, that is, the fingerprint 700,based on the light quantity difference of the reached lights. In oneexample, the sensor part 400 may be provided to have a transparentproperty.

In one example, the device may comprise a display and a sensor partsimultaneously. In this case, the device may sequentially comprise thesensor part and the sheet 600, or may sequentially comprise the sensorpart, the display and the sheet 600. In addition, any one of the displayand the sensor part may also form one layer with the light source part500.

FIG. 2 is an image of a fingerprint photographed using a sheet accordingto one embodiment of the present application. As the sheet used forphotographing, a laminate sequentially comprising a lower base layerhaving a refractive index of 1.41 for light having a wavelength of 532nm, a light control layer including a holographic film having arefractive index of 1.50 for light having a wavelength of 532 nm and aglass base layer (cover glass) having a refractive index of 1.51 forlight having a wavelength of 532 nm was used. In the case of the lightcontrol layer, it was produced using a known photopolymer film.Specifically, a diffraction pattern was recorded on the light controllayer, so that the first light control part could emit the incidentlight with 73° based on the normal to the sheet (transparent base layer)and the second light control part could emit some of the incident lightwith an angle of 45° based on the normal to the sheet (transparent baselayer. Thereafter, the sheet was irradiated with an external light with0° based on the normal to the sheet (transparent base layer), and theimage appearing at the bottom of the lower base layer by contacting afingerprint with the surface of the transparent base layer wasphotographed with a CCD (charge-coupled device).

As described above, the invention of the present application has beendescribed with reference to FIGS. 1 and 2 which are exemplaryembodiments of the present application, but the scope of protection ofthe present invention is not limited to the above-described specificembodiments and drawings. In addition, it will be understood by thosehaving ordinary knowledge in the technical field to which the presenttechnical field pertains that the inventions described in the claims canbe changed or modified variously within the technical spirit and scopeof the present invention as filed.

The invention claimed is:
 1. A method comprising: receiving, at adigital device, a user input corresponding to one or more fingerprintsof a user, the user input being received at a touch-screen displaycomprising an optical fingerprint recognition sheet on a fingerprintcontact portion, and a sheet comprising: a lower base layer and a lightcontrol layer positioned on top of the lower base layer and having afirst light control part and a second light control part, wherein anupper surface of the first light control part is adapted to transmitlight received at a first incident angle (θ₀) from the lower base layerthrough the upper surface of the first light control part at a secondincident angle (θ_(A)) different from the first incident angle (θ₀), andwherein a lower surface of the second light control part is adapted toreflect light received at the second incident angle (θ_(A)) back at boththe second incident angle (θ_(A)) and a third incident angle (θ_(B))different from the second incident angle (θ_(A)), and wherein the lowersurface of the second light control part is further adapted to transmitlight received at the third incident angle (θ_(B)), through the lowersurface of the second light control part at the third incident angle(θ_(B)), identifying, by the digital device, the one or morefingerprints received at the touch-screen display of the device from thelight with the third incident angle (θ_(B)); and executing a command, bythe digital device, in response to identification of the one or morefingerprints.
 2. The method according to claim 1, wherein executing thecommand comprises applying one or more heuristic methods.
 3. The methodaccording to claim 1, wherein the command is one or a combination of: aone-dimensional vertical screen scrolling command, a two-dimensionalscreen translation command, a screen enlargement or reduction command, acommand to convert from displaying a first item in an item set todisplaying a next item in the item set, or a command to convert fromdisplaying a first item in an item set to displaying a previous item inthe item set.
 4. The method according to claim 1, wherein the command isa user-selected command or a user-designated command.
 5. The methodaccording to claim 1, wherein the touch-screen display comprises apressure sensor on the back of the touch-screen display, and wherein themethod further comprises detecting, using the pressure sensor, apressure exerted by the one or more fingerprints on the touch-screendisplay, and wherein executing the command is based at least in part onthe pressure detected by the pressure sensor.
 6. The method according toclaim 5, wherein executing the command is in part response to the sensedpressure equaling a preset pressure.
 7. The method according to claim 1,wherein the digital device comprises a motion sensor, and wherein themethod further comprises detecting, using the motion sensor, a movementof the user, and wherein executing the command is based at least in parton the movement detected by the motion sensor.
 8. The method accordingto claim 7, wherein executing the command is in part response to thedetected movement corresponding to a predetermined movement preset inthe digital device.
 9. The method according to claim 1, wherein thesheet further comprises a transparent base layer, and comprises thelower base layer, the light control layer and the transparent base layersequentially.
 10. The method according to claim 9, further comprising,transmitting the light incident on the lower surface of the first lightcontrol part at the first incident angle (θ₀) through the lower baselayer as the light with the second incident angle (θ_(A)) different fromthe first incident angle (θ₀) toward the transparent base layer, andtransmitting the light incident on the upper surface of the second lightcontrol part at the second incident angle (θ_(A)) through thetransparent base layer as the light with the second incident angle(θ_(A)) and the light with the third incident angle (θ_(B)) differentfrom the second incident angle (θ_(A)) toward the transparent baselayer.
 11. The method according to claim 10, wherein each of the firstlight control part and the second light control part on which theincident light is transmitted comprises a respective diffractive opticalelement or a refractive optical element.
 12. The method according toclaim 11, wherein each of the first light control part and the secondlight control part on which the incident light is transmitted comprisesa respective holographic film.
 13. The method according to claim 11,wherein the light with the angle (θ_(A)) emitted from the first lightcontrol part is totally reflected from both of the upper surface of thetransparent base layer and the upper surface of the lower base layer bysatisfying:θ_(A)>(180°/π)×sin⁻¹(n ₀ /n ₁)and:θ_(A)>(180°/π)×sin⁻¹(n ₃ /n ₁) wherein, n₀ is the refractive index ofair, n₁ is the refractive index of the transparent base layer and n₃ isthe refractive index of the lower base layer.
 14. The method accordingto claim 13, wherein the light with the angle (θ_(A)) emitted from thefirst light control part is totally reflected from the upper surface ofthe transparent base layer and then penetrate the upper surface of thelight control layer by satisfying:θ_(A)<(180°/π)×sin⁻¹(n ₂ /n ₁) wherein, n₁ is the refractive index ofthe transparent base layer, n₂ is the refractive index of the firstlight control part or the second light control part in the light controllayer, and n₁ is larger than n₂.
 15. The method according to claim 14,wherein when an object having a pattern with a different height contactsthe transparent base layer, the light with the angle (θ_(A)) emittedfrom the first light control part is totally reflected from the uppersurface of the transparent base layer that the transparent base layerand the object contact directly by satisfying:θ_(A)>(180°/π)×sin⁻¹(n _(h) /n ₁) wherein, n₁ is the refractive index ofthe transparent base layer and n_(h) is the refractive index of theportion whose the object having a pattern with a different height is indirect contact with the transparent base layer.
 16. The method accordingto claim 15, wherein when the object having a pattern with a differentheight contacts the transparent base layer, the light with the angle(θ_(B)) emitted from the second light control part is totally reflectedfrom the upper surface of the transparent base layer in contact with airby satisfying:θ_(B)>(180°/π)×sin⁻¹(n ₀ /n ₁) and the light with the angle (θ_(B))emitted from the second light control part can penetrate the uppersurface of the transparent base layer that the transparent base layerand the object contact directly by satisfying:θ_(B)<(180°/π)×sin⁻¹(n _(h) /n ₁) wherein, n₀ is the refractive index ofair, n₁ is the refractive index of the transparent base layer and n_(h)is the refractive index of the portion whose the object having a patternwith a different height is in direct contact with the transparent baselayer.
 17. The method according to claim 1, wherein the sheet isprovided such that the light with the angle (θ_(B)) emitted from thesecond light control part is totally reflected from the upper surface ofthe transparent base layer and then penetrate the upper surface of thelight control layer by satisfying:θ_(B)<(180°/π)×sin⁻¹(n ₂ /n ₁) wherein, n₁ is the refractive index ofthe transparent base layer, n₂ is the refractive index of the firstlight control part or the second light control part in the light controllayer and n₁ is larger than n₂.
 18. The method according to claim 17,wherein the light with the angle (θ_(B)) emitted from the second lightcontrol part is totally reflected from the upper surface of thetransparent base layer to penetrate the light control layer and thelower base layer by satisfying:θ_(B)<(180°/π)×sin⁻¹(n ₃ /n ₁) wherein, n₁ is the refractive index ofthe transparent base layer and n₃ is the refractive index of the lowerbase layer.
 19. The method according to claim 1, wherein the digitaldevice further comprises a light source part and the light source partis located on the opposite one surface of one surface of the lower baselayer where the first light control part contacts.
 20. The methodaccording to claim 19, further comprising the light source parttransmitting vertical light to the first light control part.